code: def test_json_reprs():
      """Test JSON representations of special values"""
      assert (
          repr(datum.xxx == None) == "(datum.xxx === null)"
      )  # noqa: E711
      assert (
          repr(datum.xxx == False) == "(datum.xxx === false)"
      )  # noqa: E712
      assert repr(datum.xxx == True) == "(datum.xxx === true)"
  
file_path: altair/tests/expr/test_expr.py
imports: import operator
  import pytest
  from altair import expr
  from altair import datum
  from altair import ExprRef
  from jsonschema.exceptions import ValidationError
label_desc: Use image node_id 6 for calling a global function with example usage: test_json_reprs() without return types